After the Sept. 11 suicide hijackings, distraught U.S. Muslim leaders feared the next casualty would be their religion.

Islam teaches peace, they told anyone who would listen in news conferences, at interfaith services and, most famously, standing in a mosque with President Bush.

But five years later, the target audience for their pleas has shifted. Now the faith’s American leaders are starting to warn fellow Muslims about a threat from within.

The 2005 subway attacks in London that investigators say were committed by British-born and -raised Muslims, and the relentless Muslim-engineered sectarian assaults on Iraqi civilians, are among the events that have convinced some U.S. Muslims to change focus.

“This sentiment of denial, that sort of came as a fever to the Muslim community after 9-11, is fading away,” said Muqtedar Khan, a political scientist at the University of Delaware and author of “American Muslims.” “They realize that there are Muslims who use terrorism, and the community is beginning to stand up to this.”

Muslim leaders point to two stark examples of the new mind-set:

l A Canadian-born Muslim man worked with police for months investigating a group of Islamic men and youths accused in June of plotting terrorist attacks in Ontario. Mubin Shaikh said he feared any violence would ultimately hurt Islam and Canadian Muslims.

Salim Al-Marati attends services at a mosque in the Islamic Center of Southern California in Los Angeles. Al-Marayati, executive director of Muslim Public Affairs Council, an advocacy group, says Muslims working closely with authorities can underscore that they are not outsiders to be feared.

l In England, it’s been widely reported that a tip from a British Muslim helped lead investigators to uncover what they said was a plan by homegrown extremists to use liquid explosives to destroy U.S.-bound planes.

Cooperation isn’t emotionally easy, as Western governments enact security policies that critics say have criminalized Islam itself.

Safiyyah Ally, a graduate student in political science at the University of Toronto, wrote recently on altmuslim.com that Shaikh, the Canadian informer, went too far.

She said the North American Muslim community “is fragile enough as is” without members “spying” on each other. Leaders should counsel Muslims against violence and report suspicious activity to police – but nothing more, she argued.

“We cannot have communities wherein individuals are paranoid of each other and turned against one another,” Ally wrote.

Yet some leaders say keeping watch for extremists protects Muslims and their civil rights.

Salam al-Marayati, executive director of Muslim Public Affairs Council, an advocacy group based in Los Angeles, says working closely with authorities underscores that Muslims are not outsiders to be feared. It also gives Muslims a way to directly air their concerns about how they’re treated by the government.

“We’re not on opposite teams,” al-Marayati said. “We’re all trying to protect our country from another terrorist attack.”